Treatments on how to proceed with DCIS diagnosis is a decision that should involve your Oncologist who knows your complete medical situation and who is best equipped to inform and advise you .The most
common treatment for DCIS is Lumpectomy and removal of additional tissue to obtain clean margins.After surgery radiation therapy is usually recommended and also Hormonal therapy (Tamoxifen) but only “if” your hormone receptor status ER/PR turns out positive.
Since you had endometriosis ablation,and Tamoxifen could increase your risk of developing Uterine cancer, you should ask your OB/GYN and Oncologist if Tamoxifen is safe or not for you.
All the best...
I was diagnosed in Nov '14 with dcis. Due to strong family hx, a rapidly growing mass, and being only 47, I opted for a double mastectomy with reconstruction in Dec '15. My pathology report detected 6 areas of invasive cancer that were undetected. It also came back triple negative so tamoxifen isn't an option for me.
Good luck in your decision, and follow your gut. There is no wrong answer for treatment.